U.S. patent application number 09/897985 was filed with the patent office on 2002-02-07 for novel lactone compounds having alicyclic structure and their manufacturing method.
This patent application is currently assigned to Shin-Etsu Chemical Co., Ltd.. Invention is credited to Hasegawa, Koji, Hatakeyama, Jun, Kinsho, Takeshi, Nakashima, Matsuo, Nishi, Tsunehiro, Tachibana, Seiichiro, Watanabe, Takeru.
Application Number | 20020016477 09/897985 |
Document ID | / |
Family ID | 18702343 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020016477 |
Kind Code |
A1 |
Kinsho, Takeshi ; et
al. |
February 7, 2002 |
Novel lactone compounds having alicyclic structure and their
manufacturing method
Abstract
Lactone compounds of formula (1) are novel and useful as
monomers to form base resins for use in chemically amplified resist
compositions adapted for micropatterning lithography. 1 Letter k is
0 or 1 and m is an integer of 1-8.
Inventors: |
Kinsho, Takeshi;
(Nakakubiki-gun, JP) ; Watanabe, Takeru;
(Nakakubiki-gun, JP) ; Hasegawa, Koji;
(Nakakubiki-gun, JP) ; Nishi, Tsunehiro;
(Nakakubiki-gun, JP) ; Nakashima, Matsuo;
(Nakakubiki-gun, JP) ; Tachibana, Seiichiro;
(Nakakubiki-gun, JP) ; Hatakeyama, Jun;
(Nakakubiki-gun, JP) |
Correspondence
Address: |
MILLEN, WHITE, ZELANO & BRANIGAN, P.C.
2200 CLARENDON BLVD.
SUITE 1400
ARLINGTON
VA
22201
US
|
Assignee: |
Shin-Etsu Chemical Co.,
Ltd.
6-1, Otemachi, 2-chome, Chiyoda-ku
Tokyo
JP
|
Family ID: |
18702343 |
Appl. No.: |
09/897985 |
Filed: |
July 5, 2001 |
Current U.S.
Class: |
549/295 |
Current CPC
Class: |
C07D 315/00 20130101;
G03F 7/0395 20130101 |
Class at
Publication: |
549/295 |
International
Class: |
C07D 37/33 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 6, 2000 |
JP |
2000-205217 |
Claims
1. A lactone compound of the following general formula (1):
22wherein k is 0 or 1 and m is an integer of 1 to 8.
2. A method for preparing a lactone compound of the following
general formula (1), comprising the steps of reacting an oxirane
compound of the following general formula (2) with a
metallomalonate to form a hydroxy diester compound of the following
general formula (3), followed by hydrolysis, decarboxylation and
lactonization: 23wherein k is 0 or 1, m is an integer of 1 to 8, R
is alkyl, M is Li, Na, K, MgY or ZnY, and Y is halogen.
3. A method for preparing a lactone compound of the following
general formula (1), comprising the steps of reacting an
organometallic compound of the following general formula (4) with a
3-alkoxycarbonylpropionyl chloride to form a keto ester compound of
the following general formula (5), followed by reduction and
lactonization: 24wherein k is 0 or 1, m is an integer of 1 to 8, R
is alkyl, M is Li, Na, K, MgY or ZnY, and Y is halogen.
4. A method for preparing a lactone compound of the following
general formula (1), comprising the steps of reacting an aldehyde
compound of the following general formula (6) with lithium
3-lithiopropionate to form a hydroxycarboxylic acid compound of the
following general formula (7), followed by lactonization: 25wherein
k is 0 or 1 and m is an integer of 1 to 8.
Description
[0001] This invention relates to novel lactone compounds useful as
monomers to form base resins for use in chemically amplified resist
compositions adapted for micropatterning lithography, and methods
for preparing the same.
BACKGROUND OF THE INVENTION
[0002] While a number of recent efforts are being made to achieve a
finer pattern rule in the drive for higher integration and
operating speeds in LSI devices, deep-ultraviolet lithography is
thought to hold particular promise as the next generation in
microfabrication technology. In particular, photolithography using
a KrF or ArF excimer laser as the light source is strongly desired
to reach the practical level as the micropatterning technique
capable of achieving a feature size of 0.3 .mu.m or less.
[0003] The resist materials for use in photolithography using light
of an excimer laser, especially ArF excimer laser having a
wavelength of 193 nm, are, of course, required to have a high
transmittance to light of that wavelength. In addition, they are
required to have an etching resistance sufficient to allow for film
thickness reduction, a high sensitivity sufficient to eliminate any
extra burden on the expensive optical material, and especially, a
high resolution sufficient to form a precise micropattern. To meet
these requirements, it is crucial to develop a base resin having a
high transparency, rigidity and reactivity. None of the currently
available polymers satisfy all of these requirements. Practically
acceptable resist materials are not yet available.
[0004] Known high transparency resins include copolymers of acrylic
or methacrylic acid derivatives and polymers containing in the
backbone an alicyclic compound derived from a norbornene
derivative. All these resins are unsatisfactory. For example,
copolymers of acrylic or methacrylic acid derivatives are
relatively easy to increase reactivity in that highly reactive
monomers can be introduced and acid labile units can be increased
as desired, but difficult to increase rigidity because of their
backbone structure. On the other hand, the polymers containing an
alicyclic compound in the backbone have rigidity within the
acceptable range, but are less reactive with acid than
poly(meth)acrylate because of their backbone structure, and
difficult to increase reactivity because of the low freedom of
polymerization. Additionally, since the backbone is highly
hydrophobic, these polymers are less adherent when applied to
substrates. Therefore, some resist compositions which are
formulated using these polymers as the base resin fail to withstand
etching although they have satisfactory sensitivity and resolution.
Some other resist compositions are highly resistant to etching, but
have low sensitivity and low resolution below the practically
acceptable level.
SUMMARY OF THE INVENTION
[0005] An object of the invention is to provide a novel lactone
compound useful as a monomer to form a polymer for use in the
formulation of a photoresist composition which exhibits firm
adhesion and high transparency when processed by photolithography
using light with a wavelength of less than 300 nm, especially ArF
excimer laser light as the light source. Another object is to
provide a method for preparing the lactone compound.
[0006] We have found that a lactone compound of formula (1) can be
prepared in high yields by a simple method to be described later,
that a polymer obtained from this lactone compound has high
transparency at the exposure wavelength of an excimer laser, and
that a resist composition comprising the polymer as a base resin is
improved in adhesion to substrates.
[0007] In one aspect, the invention provides a lactone compound of
the following general formula (1). 2
[0008] Herein, k is 0 or 1 and m is an integer of 1 to 8.
[0009] In another aspect, the invention provides methods for
preparing the lactone compound of formula (1).
[0010] A first method for preparing a lactone compound of formula
(1) according to the invention involves the steps of reacting an
oxirane compound of the following general formula (2) with a
metallomalonate to form a hydroxy diester compound of the following
general formula (3), followed by hydrolysis, decarboxylation and
lactonization. 3
[0011] Herein, k and m are as defined above, R is alkyl such as
methyl, ethyl or t-butyl, M is Li, Na, K, MgY or ZnY, and Y is
halogen.
[0012] A second method for preparing a lactone compound of formula
(1) according to the invention involves the steps of reacting an
organometallic compound of the following general formula (4) with a
3-alkoxycarbonylpropionyl chloride to form a keto ester compound of
the following general formula (5), followed by reduction and
lactonization. 4
[0013] Herein, k, m, R and M are as defined above.
[0014] A third method for preparing a lactone compound of formula
(1) according to the invention involves the steps of reacting an
aldehyde compound of the following general formula (6) with lithium
3-lithiopropionate to form a hydroxycarboxylic acid compound of the
following general formula (7), followed by lactonization. 5
[0015] Herein, k and m are as defined above.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] The lactone compounds of the invention are of the following
general formula (1). 6
[0017] Herein k is 0 or 1 and m is an integer of 1 to 8 (i.e.,
1.ltoreq.m.ltoreq.8).
[0018] Illustrative examples of the lactone compound are 7
[0019] It is believed that resist polymers obtained using these
lactone compounds as the monomer exhibit good adhesion to
substrates because the butyrolactone moiety regarded as a polar
group that brings out adhesion is positioned at a site separated
apart from the polymer backbone by an alkylene group. By selecting
a lactone compound having an optimum alkylene chain as the monomer
to form a polymer, the polymer as a whole can be adjusted to an
appropriate compatibility and controlled in dissolution
properties.
[0020] The lactone compounds of the invention can be produced by
the following three methods, for example, but the invention is not
limited to these methods.
[0021] The first method involves the steps of reacting an oxirane
compound (2) with a metallomalonate to form a hydroxy diester
compound (3), followed by hydrolysis, decarboxylation and
lactonization, thereby producing the desired lactone compound (1).
8
[0022] Herein k and m are as defined above, R is an alkyl group
such as methyl, ethyl or t-butyl, M is Li, Na, K, MgY or ZnY, and Y
is a halogen atom.
[0023] The first step is to add a metallomalonate, prepared by a
conventional method, to an oxirane compound (2) to form a hydroxy
diester compound (3). 9
[0024] Ring opening of the oxirane ring occurs preferentially from
the desired methylene terminal side over the sterically hindered
methine side. The amount of metallomalonate used is preferably 0.9
to 3 mol, more preferably 1.0 to 1.8 mol per mol of the oxirane
compound. Depending on reaction conditions, a solvent may be
selected from ethers such as tetrahydrofuran, diethyl ether,
di-n-butyl ether and 1,4-dioxane, hydrocarbons such as n-hexane,
n-heptane, benzene, toluene, xylene and cumene, alcohols such as
methanol, ethanol, isopropyl alcohol and tert-butyl alcohol, and
polar aprotic solvents such as dimethyl sulfoxide and
N,N-dimethylformamide, alone or in admixture of any. The reaction
temperature and time vary over a wide range. In one example wherein
sodium anions which are prepared from malonate and sodium alkoxide
in dry alcohol are used as a reagent, the reaction temperature
preferred for rapidly driving the reaction to completion is from
room temperature to the reflux temperature, and especially from
50.degree. C. to the reflux temperature. The reaction time is
desirably determined by monitoring the reaction until the
completion by gas chromatography (GC) or silica gel thin-layer
chromatography (TLC) because higher yields are expectable. The
reaction time is usually about 1 to about 20 hours. From the
reaction mixture, the hydroxy diester compound (3) is obtained by a
conventional aqueous work-up procedure. If necessary, the compound
(3) may be purified by any conventional technique such as
distillation, chromatography or recrystallization. Often the crude
product has a sufficient purity as a substrate for the subsequent
step and can be thus used in the subsequent step without
purification.
[0025] The second step involves hydrolysis, decarboxylation and
lactonization (dehydrative condensation) to yield the desired
lactone compound (1). 10
[0026] In an example wherein the alkyl group of the malonate used
is a primary alkyl group such as methyl or ethyl (that is,
R=CH.sub.3 or C.sub.2H.sub.5), the ester is hydrolyzed or
saponified using an aqueous alkaline solution, and then neutralized
to form a hydroxy dicarboxylic acid. The resulting hydroxy
dicarboxylic acid is converted to the lactone compound by heating
in the presence of an acid catalyst to effect simultaneous
decarboxylation and cyclization. 11
[0027] Herein, k and m are as defined above, and R is a primary
alkyl group such as methyl or ethyl.
[0028] For the alkaline hydrolysis, use of aqueous solutions of
hydroxides such as sodium hydroxide, potassium hydroxide, lithium
hydroxide and barium hydroxide is preferred. The aqueous alkaline
solution is preferably used in an amount of 2 to 10 mol, especially
2 to 4 mol per mol of the hydroxy diester compound (3). Alkaline
hydrolysis can be effected in a solventless system although use may
be made of organic solvents including ethers such as
tetrahydrofuran, diethyl ether, di-n-butyl ether and 1,4-dioxane,
alcohols such as methanol, ethanol, isopropyl alcohol and
tert-butyl alcohol, and hydrocarbons such as n-hexane, n-heptane,
benzene, toluene, xylene and cumene. The reaction temperature for
alkaline hydrolysis is generally in the range of 0 to 100.degree.
C., and heating at a temperature of 50 to 100.degree. C. is
preferred to achieve rapid progress of reaction. Examples of the
acid used for neutralization and decarboxylation/lactonization
include inorganic acids such as hydrochloric acid, hydrobromic
acid, sulfuric acid and nitric acid and organic acids such as
oxalic acid, p-toluenesulfonic acid, and benzenesulfonic acid. As
the acid catalyst for promoting decarboxylation/lactonization, the
excess of acid left at the end of neutralization may be utilized or
an acid of the same or different type may be newly added. In either
case, the acid is used in an amount of 0.01 to 10 mol, especially
0.1 to 0.5 mol per mol of the hydroxy dicarboxylic acid. The
reaction can be accelerated by positively removing the water formed
upon lactone cyclization from the reaction system, for example, by
azeotropical removal of water using a hydrocarbon such as n-hexane,
n-heptane, benzene, toluene, xylene or cumene. Alternatively, the
reaction may be carried out in vacuum in order to accelerate
decarboxylation.
[0029] In another example wherein the alkyl group of the malonate
used is a tertiary alkyl group such as tert-butyl (that is,
R=t-C.sub.4H.sub.9), elimination of the tertiary alkyl group,
decarboxylation and lactonization (dehydrative condensation) can be
carried out simultaneously under acidic conditions, not by way of
alkaline hydrolysis. 12
[0030] Herein, k and m are as defined above, and R is a tertiary
alkyl group such as t-butyl. (R--H) is an alkene corresponding to
the alkyl group R from which a hydrogen atom is eliminated. For
example, (R--H) is isobutene when R is t-butyl.
[0031] Herein, an acid selected from inorganic acids such as
hydrochloric acid, hydrobromic acid, sulfuric acid and nitric acid
and organic acids such as oxalic acid, p-toluenesulfonic acid, and
benzenesulfonic acid is used in an amount of 0.01 to 10 mol,
preferably 0.1 to 0.5 mol per mol of the hydroxy diester compound.
The reaction can be accelerated by positively removing the water
formed upon lactone cyclization from the reaction system, for
example, by azeotropical removal of water using a hydrocarbon such
as n-hexane, n-heptane, benzene, toluene, xylene or cumene.
Alternatively, the reaction may be carried out in vacuum in order
to accelerate decarboxylation.
[0032] From the reaction mixture, the target lactone compound (1)
is obtained by a conventional aqueous work-up step. If necessary,
the compound (1) can be purified by any conventional technique such
as distillation, chromatography or recrystallization.
[0033] In the second method, the desired lactone compound (1) is
prepared by reacting an organometallic compound (4) with a
3-alkoxycarbonylpropion- yl chloride to form a keto ester compound
(5), followed by reduction and lactonization (dehydrative
condensation). 13
[0034] Herein, k, m, R and M are as defined above.
[0035] The first step is to react an organometallic compound (4)
with a 3-alkoxycarbonylpropionyl chloride in a solvent to form a
keto ester compound (5). 14
[0036] It is important at this stage that reaction takes place
preferentially at the acid chloride site rather than at the ester
site of the 3-alkoxycarbonylpropionyl chloride. This is
accomplished by properly selecting the type of organometallic
reagent, catalyst and reaction conditions.
[0037] The organometallic compound is prepared by a conventional
method from a corresponding halogen compound or by transmetallation
from an organometallic reagent of different metal. The solvent may
be selected in accordance with reaction conditions from ethers such
as tetrahydrofuran, diethyl ether, di-n-butyl ether and
1,4-dioxane, hydrocarbons such as n-hexane, n-heptane, benzene,
toluene, xylene and cumene, and polar aprotic solvents such as
dimethyl sulfoxide and N,N-dimethylformamide, alone or in admixture
of any. There may be used as an auxiliary a compound having a
ligand such as N,N,N',N'-tetramethylethylenediamine (TMEDA),
hexamethylphosphoric triamide (HMPA), N,N'-dimethylpropyleneurea
(DMPU) or 1,3-dimethyl-2-imidazolidinone (DMI). The catalyst which
can be used is selected from compounds of transition metals such as
iron, copper, palladium, nickel, cadmium and vanadium. An
appropriate amount of the 3-alkoxycarbonylpropionyl chloride used
is 1.0 to 5 mol, preferably 1.3 to 2 mol per mol of the
organometallic reagent.
[0038] Reaction conditions vary over a wide range depending on the
combination of reagent, solvent and catalyst. In one example using
tetrahydrofuran as the solvent and a Grignard reagent
(corresponding to M=MgY) as the organometallic compound, in the
absence of the transition metal catalyst, reaction is effected at a
low temperature, specifically -78.degree. C. to room temperature,
and especially -70.degree. C. to 0.degree. C. In this example,
dropwise addition of the Grignard reagent to the
3-alkoxycarbonylpropionyl chloride solution, known as reverse
addition, is effective. In another example using tetrahydrofuran as
the solvent, a Grignard reagent (corresponding to M=MgY) as the
organometallic compound, and an iron salt (e.g., Fe(acac).sub.3) as
the transition metal catalyst in a catalytic amount (e.g., 0.01 to
0.5 mol per mol of the Grignard reagent), reaction is effected at a
temperature of -10.degree. C. to 50.degree. C., and especially
0.degree. C. to 30.degree. C. In a further example using
tetrahydrofuran or N,N-dimethylformamide as the solvent, an
organozinc reagent (corresponding to M=ZnY) as the organometallic
compound, and a palladium compound (e.g., Pd(PPh.sub.3).sub.4) or
nickel compound (e.g., NiCl.sub.2(dppp)) as the transition metal
catalyst in a catalytic amount (e.g., 0.01 to 0.5 mol per mol of
the organozinc reagent), reaction is effected at a temperature of
0.degree. C. to 80.degree. C., and especially room temperature to
50.degree. C. In a still further example using a Grignard reagent
(corresponding to M=MgY) or organic lithium reagent (corresponding
to M=Li) as the organometallic compound, and a cuprous salt (e.g.,
CuCl or CuBr) as the transition metal catalyst in a stoichiometric
amount (e.g., 1.0 to 2.0 mol per mol of the organometallic
reagent), reaction is effected at a temperature of 0.degree. C. to
80.degree. C., and especially room temperature to 50.degree. C. The
reaction time is desirably determined by monitoring the reaction
until the completion by GC or silica gel TLC because higher yields
are expectable. The reaction time is usually about 1 to about 20
hours.
[0039] From the reaction mixture, the keto ester compound (5) is
obtained by a conventional aqueous work-up procedure. If necessary,
the end compound (5) is purified by any conventional technique such
as distillation, chromatography or recrystallization. If the crude
product has a sufficient purity as a substrate for to the
subsequent step, it can be used in the subsequent step without
purification.
[0040] The second step involves reduction and lactonization of the
keto ester compound (5) to the desired lactone compound (1). 15
[0041] First referring to the reduction of keto group, it is
important to selectively reduce only the keto group without
reducing the ester group. 16
[0042] For the reduction of keto group, various reducing agents may
be used. Often metal hydrides are preferably used in solvents.
Exemplary metal hydrides are complex hydrides and alkoxy or alkyl
derivatives thereof, including sodium borohydride, lithium
borohydride, potassium borohydride, calcium borohydride, sodium
aluminum hydride, lithium aluminum hydride, sodium
trimethoxyborohydride, lithium trimethoxyaluminum hydride, lithium
diethoxyaluminum hydride, lithium tri-t-butoxyaluminum hydride,
sodium bis(2-methoxyethoxy)aluminum hydride, and lithium
triethylboron hydride. The reducing agent is often used in an
amount of 1.0 to 8.0 mol, preferably 1.0 to 1.5 mol of hydride per
mol of the keto ester compound. The solvent may be selected in
accordance with reaction conditions from water and various organic
solvents including ethers such as tetrahydrofuran, diethyl ether,
di-n-butyl ether and 1,4-dioxane, hydrocarbons such as n-hexane,
n-heptane, benzene, toluene, xylene and cumene, alcohols such as
methanol, ethanol, isopropyl alcohol and tert-butyl alcohol, and
aprotic polar solvents such as dimethyl sulfoxide and
N,N-dimethylformamide, alone or in admixture of any.
[0043] Reaction temperature and time vary over a wide range
depending on the particular starting materials used. For example,
when reduction is effected with lithium aluminum hydride in
tetrahydrofuran, preferred reaction conditions include use of
lithium aluminum hydride in a stoichiometric or slightly excess
amount (1.0 to 1.05 equivalent as hydride) in order to avoid
further reduction, a reaction temperature in the range of
-80.degree. C. to 0.degree. C., and a reaction time of about 0.1 to
1 hour. From the reaction mixture, the hydroxy ester compound is
obtained by conventional work-up. If necessary, the product may be
purified by any conventional technique such as distillation,
chromatography or recrystallization. If the crude product has a
sufficient purity as a substrate for the subsequent step, it can be
used in the subsequent step without purification. The hydroxy ester
compound thus obtained is then converted to the desired lactone
compound (1). 17
[0044] Herein, the hydroxy ester compound can be converted to the
lactone compound by hydrolyzing or saponifying the ester with an
aqueous alkaline solution, then neutralizing it to form a hydroxy
carboxylic acid, and heating the hydroxycarboxylic acid in the
presence of an acid catalyst to effect dehydrative condensation.
Alternatively, the hydroxy ester compound can be converted to the
lactone compound by heating it in the presence of an acid catalyst
to effect alcohol-eliminating condensation. To these reactions, the
same procedure as the step of converting the hydroxy diester
compound (3) to the lactone compound (1) in the first method is
applicable.
[0045] In the third method, the lactone compound (1) is prepared by
reacting an aldehyde compound (6) with lithium 3-lithiopropionate
to form a hydroxycarboxylic acid compound (7), followed by
lactonization (dehydrative condensation). 18
[0046] Herein k and m are as defined above.
[0047] The first step is to react an aldehyde compound (6) with
lithium 3-lithiopropionate to form a hydroxycarboxylic acid
compound (7). 19
[0048] Lithium 3-lithiopropionate (dianion) is prepared by
treatment of a 3-halopropionic acid with a base in a solvent.
Examples of the 3-halopropionic acid are 3-bromopropionic acid and
3-iodopropionic acid. Examples of the base include lithium amides
such as lithium diisopropylamide, lithium
2,2,6,6-tetramethylpiperidine, lithium bistrimethylsilylamide and
lithium isopropylcyclohexylamide; alkyl lithium compounds such as
trityllithium, methyllithium, phenyllithium, sec-butyllithium and
tert-butyllithium; and lithium hydride. The solvent is selected in
accordance with reaction conditions from ethers such as
tetrahydrofuran, diethyl ether, di-n-butyl ether and 1,4-dioxane,
hydrocarbons such as n-hexane, n-heptane, benzene, toluene, xylene
and cumene, and polar aprotic solvents such as dimethyl sulfoxide
and N,N-dimethylformamide, alone or in admixture of any. There may
be used as an auxiliary a compound having a ligand such as
N,N,N',N'-tetramethylethy- lenediamine (TMEDA),
hexamethylphosphoric triamide (HMPA), N,N'-dimethylpropyleneurea
(DMPU) or 1,3-dimethyl-2-imidazolidinone (DMI).
[0049] The lithium 3-lithiopropionate thus prepared is used in an
amount of 0.7 to 3 mol, preferably 1.0 to 1.3 mol per mol of the
aldehyde compound (6) for addition reaction to take place. Since
the lithium 3-lithiopropionate is unstable at high temperature, the
reaction is preferably effected under cooling, especially at a
temperature of -78.degree. C. to 0.degree. C. The reaction time is
desirably determined by monitoring the reaction until the
completion by GC or silica gel TLC because higher yields are
expectable. The reaction time is usually about 0.2 to about 2
hours. From the reaction mixture, the hydroxycarboxylic acid
compound (7) is obtained by a conventional aqueous work-up step. If
necessary, the compound (7) may be purified by any conventional
technique such as distillation, chromatography or
recrystallization. If the crude product has a sufficient purity as
a substrate for the subsequent step, it can be used in the
subsequent step without purification.
[0050] The second step involves lactonization (dehydrative
condensation) of the hydroxycarboxylic acid compound (7) to the
desired lactone compound (1). 20
[0051] The hydroxycarboxylic acid compound can be converted to the
lactone compound by heating it in the presence of an acid catalyst
to effect dehydrative condensation. To this reaction, the same
procedure as the step of converting the hydroxy dicarboxylic acid
compound to the lactone compound (1) in the first method is
applicable.
[0052] A polymer is prepared using the inventive lactone compound
as a monomer. The method is generally by mixing the monomer with a
solvent, adding a catalyst or polymerization initiator, and
effecting polymerization reaction while heating or cooling the
system if necessary. This polymerization reaction can be effected
in a conventional way. Exemplary polymerization processes are
ring-opening metathesis polymerization, addition polymerization,
and alternating copolymerization with maleic anhydride or
maleimide. It is also possible to copolymerize the lactone compound
with another norbornene monomer.
[0053] A resist composition is formulated using as a base resin the
polymer resulting from polymerization of the lactone compound.
Usually, the resist composition is formulated by adding an organic
solvent and a photoacid generator to the polymer and if necessary,
further adding a crosslinker, a basic compound, a dissolution
inhibitor and other additives. Preparation of the resist
composition can be effected in a conventional way.
[0054] The resist composition formulated using the polymer
resulting from polymerization of the inventive lactone compound
lends itself to micropatterning with electron beams or deep-UV rays
since it is sensitive to high-energy radiation and has excellent
sensitivity, resolution, and etching resistance. Especially because
of the minimized absorption at the exposure wavelength of an ArF or
KrF excimer laser and firm adhesion to the substrate, a finely
defined pattern having sidewalls perpendicular to the substrate can
easily be formed. The resist composition is thus suitable as
micropatterning material for VLSI fabrication.
EXAMPLE
[0055] Synthesis Examples and Reference Examples are given below
for further illustrating the invention. It is not construed that
the invention be limited to these examples.
[0056] Synthesis Examples are first described. Lactone compounds
within the scope of the invention were synthesized in accordance
with the following formulation.
Synthesis Example 1
Synthesis of .gamma.-(5-norbornen-2-yl)methyl-.gamma.-butyrolactone
(Monomer 1)
[0057] In a nitrogen atmosphere, a solution in 300 g dry
tetrahydrofuran of a Grignard reagent prepared from 50.0 g of
5-bromomethyl-2-norbornene by a conventional technique was added to
a mixture of 47.2 g of 3-methoxycarbonyl-propionyl chloride, 4.61 g
of iron (III) acetylacetonate, and 300 ml of dry tetrahydrofuran at
10.degree. C., which was stirred for 2 hours. Then 100 g of 10%
hydrochloric acid was added to stop the reaction, whereupon hexane
was added for extraction. The organic layer was washed with water
and aqueous saturated sodium bicarbonate solution, and concentrated
in vacuum, obtaining a keto ester. The keto ester was dissolved in
100 g of tetrahydrofuran, to which 80 g of water, 5.06 g of sodium
boron hydride and 10 g of methanol were successively added. The
mixture was stirred for 12 hours at 20.degree. C. for effecting
reduction to a hydroxy ester. Then 50 g of 20% hydrochloric acid
was added to the reaction mixture, which was stirred for one hour
for lactonization. This was followed by hexane extraction, washing
with water, washing with aqueous saturated sodium bicarbonate
solution, and vacuum concentration. Purification by silica gel
column chromatography yielded 42.1 g (yield 82%) of
.gamma.-(5-norbornen-2-yl)methyl-.gamma.-bu- tyrolactone.
[0058] IR (thin film): .nu.=3057, 2962, 2939, 2866, 1774, 1336,
1217, 1180, 1020, 978, 912 cm.sup.-1
[0059] .sup.1H-NMR of major endo-isomer (270 MHz in CDCl.sub.3):
.delta.=0.54 (1H, m), 1.15-1.45 (3H, m), 1.45-1.95 (3H, m),
2.15-2.40 (2H, m), 2.40-2.60 (2H, m), 2.70-2.85 (2H, m), 4.46 (1H,
m), 5.90 (1H, m), 6.13 (1H, m).
Synthesis Example 2
Synthesis of .gamma.-(5-norbornen-2-yl)methyl-.gamma.-butyrolactone
(Monomer 1)
[0060] In 80 g of dry tetrahydrofuran was dissolved 10.0 g of
3-bromopropionic acid. In a nitrogen atmosphere, 85.0 g of a hexane
solution of 1.6M n-butyllithium was added to the solution at
-78.degree. C., followed by 30 minutes of stirring. Then a solution
of 8.92 g 2-(5-norbornen-2-yl)acetaldehyde in 20 g
hexamethylphosphoric triamide was added dropwise to the solution at
the same temperature. With stirring, the temperature of the
solution was gradually raised to 20.degree. C. over 2 hours. Next,
80 g of 5% hydrochloric acid was added to the solution, which was
stirred for one hour for lactonization. The organic layer was
separated, washed with aqueous saturated sodium bicarbonate
solution, washed with water, and concentrated in vacuum.
Purification by silica gel column chromatography yielded 8.17 g
(yield 65%) of
.gamma.-(5-norbornen-2-yl)methyl-.gamma.-butyrolactone. The
analytical properties of this compound were substantially identical
with the data of Synthesis Example 1.
Synthesis Example 3
Synthesis of
.gamma.-2-(5-norbornen-2-yl)ethyl-.gamma.-butyrolactone (Monomer
2)
[0061] In a nitrogen atmosphere, 1.84 g of metallic sodium was
dissolved in 100 g of dry ethanol. Then 13.0 g of diethyl malonate
was added to the solution, which was heated under reflux for one
hour, forming the sodium salt of diethyl malonate. Then 11.2 g of
1,2-epoxy-4-(5-norbornen-2-yl)bu- tane was added to the solution,
which was heated under reflux for 4 hours, forming a hydroxy
diester compound. Then 130 g of a 5% aqueous sodium hydroxide
solution was added to the solution, which was heated under reflux
for 4 hours to effect hydrolysis. The ethanol was distilled off,
and 100 g of toluene and 60 g of 20% hydrochloric acid were added
to the residue, which was stirred for one hour for lactonization,
forming a lactone carboxylic acid. The organic layer was separated
and concentrated in vacuum. Decarboxylation reaction was effected
at 140.degree. C. and 8,000 Pa. Subsequent vacuum distillation
yielded 12.6 g of
.gamma.-2-(5-norbornen-2-yl)ethyl-.gamma.-butyrolactone (boiling
point: 122-127.degree. C./67 Pa, yield: 89%).
[0062] IR (thin film): .nu.=3055, 2960, 2937, 2864, 1776, 1456,
1352, 1219, 1180, 1018, 982, 912 cm.sup.-1
[0063] .sup.1H-NMR of major endo-isomer (270 MHz in CDCl.sub.3):
.delta.0.49 (1H, m), 1.00-1.90 (8H, m), 1.97 (1H, m), 2.28 (1H, m),
2.45-2.55 (2H, m), 2.70-2.80 (2H, m), 4.42 (1H, m), 5.89 (1H, m),
6.11 (1H, m).
Synthesis Example 4
Synthesis of
.gamma.-2-(5-norbornen-2-yl)ethyl-.gamma.-butyrolactone (Monomer
2)
[0064] In a nitrogen atmosphere, 11.2 g of potassium t-butoxide was
dissolved in 250 g of dry tetrahydrofuran. Then 21.0 g of
di-t-butyl malonate and 8.0 g of
1,2-epoxy-4-(5-norbornen-2-yl)butane were successively added to the
solution, which was heated under reflux for 10 hours. The reaction
solution was neutralized with 100 g of a 10% aqueous acetic acid
solution, and extracted with ethyl acetate, whereupon the extracted
solution was washed with water and concentrated in vacuum,
obtaining a hydroxy diester compound. The hydroxy diester compound
was dissolved in 200 g of toluene, which was combined with 1.0 g of
p-toluenesulfonic acid and heated under reflux for 10 hours for
effecting ester decomposition, lactonization and decarboxylation
reaction. The reaction mixture was washed with water and
concentrated in vacuum. Purification by vacuum distillation yielded
6.00 g (yield 60%) of
.gamma.-2-(5-norbornen-2-yl)ethyl-.gamma.-butyrolactone. The
analytical properties of this compound were substantially identical
with the data of Synthesis Example 3.
Synthesis Example 5
Synthesis of
.gamma.-{5-(5-norbornen-2-yl)-1-pentyl}-.gamma.-butyrolactone
(Monomer 3)
[0065] In a nitrogen atmosphere, a solution in 300 g dry
tetrahydrofuran of a Grignard reagent prepared from 91.8 g of
5-(5-chloro-1-pentyl)-2-nor- bornene by a conventional technique
was added to a suspension of 69.3 g zinc chloride in 200 g dry
tetrahydrofuran, forming an organozinc reagent. In the nitrogen
atmosphere, the organozinc reagent was added to a mixture of 83.5 g
of 3-methoxycarbonylpropionyl chloride, 5.0 g of
tetrakis(triphenylphosphine)palladium(0), and 200 g of dry
tetrahydrofuran at 20.degree. C., which was stirred for 4 hours.
Then 500 g of 10% aqueous ammonium chloride solution was added to
stop the reaction, followed by hexane extraction, water washing and
vacuum concentration, obtaining a keto ester compound. The keto
ester compound was subjected to reduction, lactonization and
purification as in Synthesis Example 1, yielding 97.5 g (yield 85%)
of
.gamma.-{5-(5-norbornen-2-yl)-1-pentyl}-.gamma.-butyrolactone.
[0066] IR (thin film): .delta.=3057, 2933, 2860, 1778, 1460, 1346,
1219, 1180, 1124, 1018, 978, 914 cm.sup.-1
[0067] .sup.1H-NMR of major endo-isomer (300 MHz in CDCl.sub.3):
.delta.=0.46 (1H, m), 0.95-2.00 (15H, m), 2.30 (1H, m), 2.40-2.60
(2H, m), 2.65-2.80 (2H, m), 4.46 (1H, m), 5.88 (1H, m), 6.08 (1H,
m).
[0068] The structural formulas of Monomers 1 to 3 are shown below.
21
Reference Example
[0069] Polymers were synthesized using the lactone compounds
obtained in the above Synthesis Examples. Using the polymers as a
base resin, resist compositions were formulated, which were
examined for substrate adhesion.
[0070] Polymerization reaction of tert-butyl
5-norbornene-2-carboxylate, Monomer 1, and maleic anhydride was
effected using an initiator V65 (Wako Junyaku K.K.), yielding an
alternating copolymer of tert-butyl
5-norbornene-2-carboxylate/.gamma.-(5-norbornen-2-yl)methyl-.gamma.-butyr-
olactone/maleic anhydride (copolymerization ratio 4/1/5).
[0071] A resist composition was prepared by blending 80 parts by
weight of the above copolymer as a base resin, 1.0 part by weight
of triphenylsulfonium trifluoromethanesulfonate as a photoacid
generator, 480 parts by weight of propylene glycol monomethyl ether
acetate as a solvent, and 0.08 part by weight of tributylamine. The
composition was spin coated on a silicon wafer having
hexamethyldisilazane sprayed thereon at 90.degree. C. for 40
seconds and heat treated at 110.degree. C. for 90 seconds, forming
a resist film of 500 nm thick. The resist film was exposed to KrF
excimer laser light, heat treated at 110.degree. C. for 90 seconds,
and developed by immersing in a 2.38% tetramethylammonium hydroxide
aqueous solution for 60 seconds, thereby forming a 1:1
line-and-space pattern. The wafer as developed was observed under
SEM, finding that the pattern down to 0.26 .mu.m size was left
unstripped.
Comparative Reference Example
[0072] For comparison purposes, a resist composition was prepared
as above, using an alternating copolymer of tert-butyl
5-norbornene-2-carboxylate/maleic anhydride (copolymerization ratio
1/1). It was similarly processed, and examined for substrate
adhesion. No patterns with a size of 0.50 .mu.m or less were
left.
[0073] It was confirmed that polymers resulting from the inventive
lactone compounds have significantly improved substrate adhesion as
compared with prior art polymers.
[0074] Japanese Patent Application No. 2000-205217 is incorporated
herein by reference.
[0075] Although some preferred embodiments have been described,
many modifications and variations may be made thereto in light of
the above teachings. It is therefore to be understood that the
invention may be practiced otherwise than as specifically described
without departing from the scope of the appended claims.
* * * * *